1. Field of the Invention
The present invention relates to a mobile machine for clearing ballast from a ballast bed section wherefrom a tie has been removed, which comprises a machine frame extending in a longitudinal direction, undercarriages supporting the machine frame for mobility on a track supported on the ballast bed, the track comprising two rails having a field side and a gage side, and a ballast clearing device vertically adjustably mounted on the machine frame for clearing ballast from the ballast bed section, the ballast clearing device comprising inner ballast clearing elements on the gage side of the rails and outer ballast clearing elements on the field side of the rails.
The invention also relates to an improved method for clearing ballast from a ballast section wherefrom a tie has been removed.
2. Description of the Prior Art
A machine of this type has been disclosed in U.S. Pat. No. 5,125,345. In this machine, the ballast clearing is combined with a tie exchange and tamping of the newly inserted tie. The ballast clearing device comprises two pairs of ballast clearing elements, each pair being associated with one of the rails and being lowered into the ballast bed after an old tie has been removed. Each pair of ballast clearing elements is then transversely moved to displace parts of the ballast to the track shoulder.
Another machine of this type has been disclosed in U.S. Pat. No. 5,046,270.
It is the primary object of this invention to provide such a ballast clearing machine and method with an improved efficiency.
This object is accomplished according to the invention with a mobile machine of the first-described type, wherein the ballast clearing device comprises an inner ballast clearing element arranged on the gage side of at least one rail and pivotal by a pivoting drive in a plane extending transversely to the longitudinal direction about an axis extending in the longitudinal direction, and an outer ballast clearing element vertically adjustable by a vertical adjustment drive independent of the inner ballast clearing element and arranged on the field side of the rail.
This simple structure of the ballast clearing device makes it possible to displace the ballast underneath the rail to its field side and towards the outer ballast clearing element, which is then enabled to displace the cleared ballast towards the track shoulder. The independent vertical adjustment of the inner and outer ballast clearing elements assures the sequential operation of the two ballast clearing elements in an advantageous manner.
The invention accordingly provides an improved method for clearing ballast from a ballast bed section wherefrom a tie has been removed, the ballast bed supporting a track comprising two rails having a field side and a gage side, which comprises clearing ballast from the ballast bed section by first clearing a part of the ballast by lowering an inner ballast clearing element carrying a ballast clearing plate into the ballast, the inner ballast clearing element being arranged on the gage side of the rail, and pivoting the inner ballast clearing element in a plane extending transversely to the longitudinal direction about an axis extending in the longitudinal direction until the ballast clearing plate has displaced said ballast part towards the field side of the rail, and then lowering an outer ballast clearing element arranged on the field side of the rail and pivoting the outer ballast clearing element to displace the ballast towards a ballast bed shoulder.
In this method, efficient ballast clearing is obtained in a relative short operating cycle, providing a rapid clearing of the ballast underneath the rails and removal of the cleared ballast to the ballast bed shoulder.